1. Field of the Invention
The present invention deals with a stacked-sheet prefeeder which removes, in a fish-scale-like mode of arrangement, a plurality of sheets from the bottom surface of a comparatively large stack of sheets and which separates these sheets subsequently.
2. Description of Prior Art
A known stacked-sheet prefeeder comprises a sheet guiding device for receiving therein a comparatively large stack of sheets, which, when seen in the direction of movement of the paper, is arranged behind an intermediate tray into which sheets are introduced which are removed from the lower surface of the stack in the form of a stack or in a scalelike mode of arrangement. In the known stacked-sheet prefeeder, individual sheets are removed from the bottom area of the intermediate tray for subsequent processing, the individual sheets being removed in the same direction of transport in which the scaled stream of sheets was introduced in the intermediate tray. It follows that in this known stacked-sheet prefeeder, which operates according to the stepwise separation principle explained hereinbefore, the stack of sheets is located behind the intermediate tray in the direction of movement of the paper or sheets of paper so that the scaled stream supplied to the intermediate tray and the stream of paper consisting of the separated sheets, which are removed from the intermediate tray, have the same direction of flow. In the known stacked-sheet prefeeder, the position of an active transport device, which removes the separated sheets from a bottom area of the intermediate tray, must be adjusted in dependence upon the format of the sheets. In other words, the transport device of the known stacked-sheet prefeeder must be readjusted in the direction of transport if the sheets become shorter in size. The adjustment operations, which are therefore required in the case of a change-over of the format processed by the stacked-sheet prefeeder, are complicated on the one hand and require a specially trained operator on the other.
German Patent 22 03 626 discloses an apparatus for removing sheets from a main stack, the apparatus comprising a removing device acting on the lower surface of the main stack, an arrangement for forming an intermediate stack of limited height, which is arranged subsequent to the removing device, and a second removing device acting on the lowermost sheet of the intermediate stack and followed by a separator device including at least two transport elements which act on the supplied sheet with different circumferential speeds as well as at least one brake means which acts on the supplied sheet from above. Furthermore, the main stack is inclined towards the intermediate stack, whereby the conveying plane of the first removing device defines an acute angle with the conveying plane of the second removing device, which extends on a lower level, a sensor switch controlling the first removing device being provided in the area of the intermediate stack for limiting the height of the intermediate stack. A stop means limiting the free movement of the sheets removed from the main stack is provided with the sensor switch. In addition, the direction of transport of the second removing device is opposite to the direction of transport of the first removing device.